For the production of concrete blocks, concrete-block-making machines are used in which a mould is filled with concrete mortar by means of a filling carriage. In this case, the filling carriage with the concrete mortar is moved horizontally right across the mould, so that the concrete mortar can fall into the mould. The filling carriage, open at the top and bottom and located below a silo, is filled in the process and moved by means of a linear drive across a table plate into a position above the mould located on a production base. In this case, the filling carriage is guided by a horizontal guide. In the process, considerable contamination occurs, which is caused by cement dust released in particular during the compacting operation and which, due to deposits, impairs the linear drive for the filling carriage and in particular the linear guide. This is countered by the filling carriage being moved with considerable play along rails by means of wheels or rollers. However, this does not permit high positioning accuracy and repetitive accuracy, which are important for a uniform block quality.